The Meadow Jumping Mouse as a Laboratory Model of Hibernation

Abstract

Hibernating mammals exhibit great metabolic flexibility. They experience seasonal obesity and employ heterothermy as a survival strategy. During hibernation in cold climates, small mammalian hibernators enter a state of metabolic torpor and profound hypothermia. The significant (>95%) reduction of metabolic rate during torpor allows the hibernator to subsist on body fat for up to six months. The physiological flexibility of hibernators and their ability to suppress metabolic rate and survive hypothermia are of interest to human medicine; however, the molecular mechanisms underlying these phenotypes are not well understood and most current hibernating model organisms are not conducive to genetic approaches due to long generation times. The goal of this research has been to establish the meadow jumping mouse (Zapus hudsonius) as a convenient laboratory model of hibernation. Meadow jumping mice are small North American rodents with a ‘true’ hibernation phenotype: they fatten prior to hibernation and undergo multi‐day bouts of torpor that are interrupted by short interbout arousals. Crucially, meadow jumping mice breed multiple times per summer in the wild, and they cue their transition from summer reproduction to fall fattening and hibernation largely on day length. We established a breeding colony using wild‐caught animals that were trapped in Massachusetts in the summers of 2014 and 2015. The animals remain in a lean breeding condition year‐round when housed at long photoperiod (16 hours light, 8 hours dark). Obesity and torpor can be induced by exposure to short photoperiod (8 hours light, 16 hours dark) and reduced temperature. We have generated the first meadow jumping mouse transcriptome data and expect that completion of ongoing genome sequencing efforts will increase the utility of this model. The meadow jumping mouse appears to be suitable for investigation of hibernation metabolism in the laboratory, and its short generation time may open the door to future genetic studies of hibernation phenotypes.Support or Funding InformationWJI acknowledges support from the Sara and Frank McKnight Fund for Biochemical Research and an NIH Early Independence Award (DP5OD021365).